U.S. patent application number 10/900458 was filed with the patent office on 2005-02-10 for module with embedded semiconductor ic and method of fabricating the module.
Invention is credited to Abe, Hisayuki, Endo, Toshikazu, Kawabata, Kenichi, Suzuki, Kei, Takano, Kosuke, Takaya, Minoru.
Application Number | 20050029642 10/900458 |
Document ID | / |
Family ID | 33545106 |
Filed Date | 2005-02-10 |
United States Patent
Application |
20050029642 |
Kind Code |
A1 |
Takaya, Minoru ; et
al. |
February 10, 2005 |
Module with embedded semiconductor IC and method of fabricating the
module
Abstract
A module with embedded semiconductor IC of the present invention
includes a first resin layer, a second resin layer, post electrodes
passing through the first and second resin layers, and a
semiconductor IC mounted as embedded between the first resin layer
and the second resin layer. Stud bumps are formed on land
electrodes of the semiconductor IC and positioned with respect to
the post electrodes. Owing to this positioning of the stud bumps
formed on the semiconductor IC with respect to the post electrodes,
the planar position of the stud bumps is substantially fixed. As a
result, it is possible to use a semiconductor IC having a very
narrow electrode pitch of 100 .mu.m or smaller, particularly of
around 60 .mu.m.
Inventors: |
Takaya, Minoru; (Tokyo,
JP) ; Abe, Hisayuki; (Tokyo, JP) ; Suzuki,
Kei; (Tokyo, JP) ; Takano, Kosuke; (Tokyo,
JP) ; Kawabata, Kenichi; (Tokyo, JP) ; Endo,
Toshikazu; (Tokyo, JP) |
Correspondence
Address: |
Wolff & King, PLLC
2111 Eisenhower Ave., Suite 402
Alexandria
VA
22314
US
|
Family ID: |
33545106 |
Appl. No.: |
10/900458 |
Filed: |
July 28, 2004 |
Current U.S.
Class: |
257/678 ;
257/E23.178 |
Current CPC
Class: |
H01L 2221/68359
20130101; H01L 2924/01038 20130101; H01L 2924/01079 20130101; H01L
24/19 20130101; H01L 24/82 20130101; H01L 2924/19041 20130101; H01L
2224/82138 20130101; H01L 2924/0104 20130101; H01L 2924/01057
20130101; H01L 2224/82039 20130101; H01L 2924/01082 20130101; H01L
2924/01078 20130101; H01L 2924/00014 20130101; H01L 2924/01013
20130101; H01L 24/18 20130101; H01L 2224/05026 20130101; H01L
2221/68363 20130101; H01L 2924/04953 20130101; H05K 1/185 20130101;
H01L 2224/1134 20130101; H01L 2924/01019 20130101; H01L 2924/01015
20130101; H01L 2924/0103 20130101; H01L 2924/01033 20130101; H01L
2924/01073 20130101; H01L 2924/30105 20130101; H01L 21/568
20130101; H01L 2224/0615 20130101; H01L 2224/16237 20130101; H01L
2924/01029 20130101; H01L 2224/04105 20130101; H01L 2924/14
20130101; H01L 2224/13099 20130101; H01L 2924/12042 20130101; H01L
2924/01005 20130101; H01L 2924/01006 20130101; H01L 23/5389
20130101; H01L 2224/18 20130101; H01L 2924/00013 20130101; H01L
2924/01041 20130101; H01L 2924/01012 20130101; H01L 2924/0102
20130101; H01L 2224/05573 20130101; H01L 2924/00013 20130101; H01L
2224/13099 20130101; H01L 2924/12042 20130101; H01L 2924/00
20130101; H01L 2924/00014 20130101; H01L 2224/05599 20130101 |
Class at
Publication: |
257/678 |
International
Class: |
H01L 023/02 |
Foreign Application Data
Date |
Code |
Application Number |
Jul 30, 2003 |
JP |
2003-283243 |
Jun 29, 2004 |
JP |
2004-191369 |
Jun 29, 2004 |
JP |
2004-191475 |
Claims
What is claimed is:
1. A module, comprising: a first resin layer; a second resin layer;
post electrodes embedded in at least the first and second resin
layers; and a semiconductor IC mounted as embedded between the
first resin layer and the second resin layer, the semiconductor IC
having stud bumps which are positioned with respect to the post
electrodes.
2. The module as claimed in claim 1, wherein said semiconductor IC
is reduced in thickness by polishing.
3. The module as claimed in claim 1, further comprising: a first
circuit board wiring pattern formed on the first resin layer side;
and a second circuit board wiring pattern formed on the second
resin layer side, the post electrodes being electrically connected
at their one ends to the first circuit board wiring pattern, and
the post electrodes being electrically connected at their other
ends to the second circuit board wiring pattern.
4. The module as claimed in claim 3, further comprising a third
circuit board wiring pattern formed to be embedded between the
first resin layer and the second resin layer.
5. The module as claimed in claim 1, wherein an electrode pitch of
the semiconductor IC is equal to or less than 100 .mu.m.
6. The module as claimed in claim 1, wherein said first resin layer
is in contact with, among surfaces of the semiconductor IC, at
least a part of opposite surface to a surface provided with the
stud bumps and at least a part of peripheral surface, the second
resin layer being in contact with at least a part of stud bumps,
the first resin layer and the second resin layer being formed of
different materials.
7. The module as claimed in claim 6, wherein the material forming
the second resin layer has a higher Q value than the material
forming the first resin layer.
8. The module as claimed in claim 6, wherein the material forming
the second resin layer has a lower dielectric constant than the
material forming the first resin layer.
9. The module as claimed in claim 6, wherein a mechanical strength
of the material forming the first resin layer is higher than that
of the material forming the second resin layer.
10. The module as claimed in claim 6, wherein a water absorption
property of the material forming the first resin layer is lower
than that of the material forming the second resin layer.
11. The module as claimed in claim 6, wherein an adhesive property
with respect to the semiconductor IC of the material forming the
first resin layer is higher than that of the material forming the
second resin layer.
12. A module, comprising: a semiconductor IC formed on its main
surface with stud bumps; a first resin layer formed in contact with
back surface and at least part of a peripheral surface of the
semiconductor IC; and a second resin layer formed in at least
partial contact with the stud bumps, the first resin layer and the
second resin layer being formed of different materials.
13. The module as claimed in claim 12, wherein the material forming
the second resin layer has a higher Q value than the material
forming the first resin layer.
14. The module as claimed in claim 12, wherein the material forming
the second resin layer has a lower dielectric constant than the
material forming the first resin layer.
15. The module as claimed in claim 12, wherein a mechanical
strength of the material forming the first resin layer is higher
than that of the material forming the second resin layer.
16. The module as claimed in claim 12, wherein a water absorption
property of the material forming the first resin layer is lower
than that of the material forming the second resin layer.
17. The module as claimed in claim 12, wherein an adhesive property
with respect to the semiconductor IC of the material forming the
first resin layer is higher than that of the material forming the
second resin layer.
18. The module as claimed in claim 12, wherein substantially all of
the back surface of the semiconductor IC is in contact with the
first resin layer, and substantially all of the main surface of the
semiconductor IC is in contact with the second resin layer.
19. The module as claimed in claim 12, wherein substantially all of
the peripheral surface of the semiconductor IC is in contact with
the first resin layer.
20. The module as claimed in claim 12, wherein said semiconductor
IC is reduced in thickness by polishing.
21. A method of fabricating a module with embedded a semiconductor
IC, comprising: a step of forming post electrodes on a first
transfer board; a step of forming first and second locating
portions on a second transfer board, a step of provisionally
attaching the semiconductor IC having stud bumps to the second
transfer board while aligning the stud bumps with the first
locating portions; and a step of using the first and second
transfer boards to press-harden a resin while using the second
locating portions and the post electrodes to align the first
transfer board with the second transfer board.
22. The method of fabricating the module as claimed in claim 21,
further comprising a step of reducing a thickness of the
semiconductor IC by polishing before provisionally attaching the
semiconductor IC to the second transfer board.
23. The method of fabricating the module as claimed in claim 21,
further comprising a step of forming a board wiring pattern on at
least one of the first transfer board and the second transfer
board.
24. The method of fabricating the module as claimed in claim 21,
further comprising: a step, following resin hardening, of detaching
the second transfer board to expose the post electrodes and stud
bumps; a step of forming a resin layer covering the exposed post
electrodes and stud bumps; a step of removing part of the resin
layer to again expose the post electrodes and stud bumps; and a
step of forming a board wiring pattern matched to the again exposed
post electrodes and stud bumps.
25. The method of fabricating the module as claimed in claim 21,
wherein said first transfer board is a multilayer substrate.
Description
TECHNICAL FIELD
[0001] The present invention relates to a module with embedded
semiconductor IC and a method of fabricating the module,
particularly to a module with embedded semiconductor IC suitable
for incorporating a semiconductor IC having a narrow electrode
pitch and a method of fabricating the module.
BACKGROUND OF THE INVENTION
[0002] The desire to realize smaller and thinner modules mounted
with semiconductor ICs has prompted numerous proposals regarding
how to mount a bare semiconductor IC chip on a printed circuit
board. A semiconductor IC in the bare-chip state has a very much
narrower electrode pitch than a packaged semiconductor IC. When it
is mounted on a printed circuit board, therefore, a need arises to
address the important issue of how to bond the electrode pads of
the semiconductor IC (sometimes called the "land electrodes" in the
following description) with the wiring of the printed circuit board
(sometimes called the "board wiring pattern").
[0003] One known method of bonding the land electrodes and board
wiring pattern is wire bonding. Although this method enables
relatively easy mounting of a bare-chip semiconductor IC, a problem
arises in that the mounting area becomes large owing to the need to
establish the region for mounting the semiconductor IC and the
region for connecting the bonding wires on different surfaces of
the printed circuit board.
[0004] Another method of connecting the land electrodes and board
wiring pattern is that of mounting the bare-chip semiconductor IC
by the flip-chip method. While this method reduces the mounting
area, it involves complicated processing, such as applying multiple
layers of under barrier metal (UBM) on the land electrodes in order
to ensure adequate mechanical bonding strength between the land
electrodes and board wiring pattern.
[0005] Moreover, both of these methods result in the semiconductor
IC being mounted on the surface of the printed circuit board. The
methods therefore have the common disadvantage of making it
difficult to reduce the overall thickness of the module. Japanese
Patent Application Laid Open No. 9-321408 ('408) teaches a method
of fabricating a module with embedded semiconductor IC by forming a
cavity in the printed circuit board and embedding a bare-chip
semiconductor IC in the cavity.
[0006] When the method of '408 is adopted, however, the thickness
of the printed circuit board needs to be increased to some degree
so as to reinforce the strength of the region where the cavity is
formed. This runs counter to the desire to make the module thinner.
In addition, the size of the cavity in the planar direction has to
be made somewhat larger than the size of the semiconductor IC in
the planar direction. The resulting shift in the positional
relationship between the land electrodes and board wiring pattern
makes it very difficult to use a semiconductor IC having an
electrode pitch of 100 .mu.m or smaller.
[0007] Thus with the conventional module with embedded
semiconductor IC, it is difficult to achieve sufficient thickness
reduction and, further, very difficult to use a semiconductor IC
having a narrow electrode pitch.
[0008] In the method taught by '408, most of the semiconductor IC
is covered by the resin layer for filling the cavity. When a
material excellent in physical properties is selected for the resin
layer, the electrical properties are inadequate, and when a
material excellent in electrical properties is selected, the
physical properties are inadequate. In the conventional module with
embedded semiconductor IC, it has therefore been hard to achieve
both good semiconductor IC physical protection and excellent
electrical properties at the same time.
SUMMARY OF THE INVENTION
[0009] It is therefore an object of the present invention to
provide a module with embedded semiconductor IC enabling marked
reduction in thickness, and a method of fabricating the module.
[0010] Another object of the present invention is to provide a
module with embedded semiconductor IC capable of using a
semiconductor IC having a very narrow electrode pitch, and a method
of fabricating the module.
[0011] Still another object of the present invention is to provide
a module with embedded semiconductor IC that achieves both good
semiconductor IC physical protection and excellent electrical
properties.
[0012] A module with embedded semiconductor IC according to one
aspect of the present invention comprises a first resin layer, a
second resin layer, post electrodes embedded in at least the first
and second resin layers, and a semiconductor IC mounted as embedded
between the first resin layer and the second resin layer, stud
bumps being formed on land electrodes of the semiconductor IC and
the stud bumps being positioned with respect to the post
electrodes.
[0013] Since the semiconductor IC is embedded between the first
resin layer and second resin layer in the present invention, the
overall thickness of the module with embedded semiconductor IC can
be reduced. Moreover, since the stud bumps formed on the
semiconductor IC are positioned with respect to the post
electrodes, the planar position of the stud bumps is substantially
fixed. As a result, it is possible to use a semiconductor IC having
a very narrow electrode pitch of 100 .mu.m or smaller, particularly
of around 60 .mu.m. If a semiconductor IC reduced in thickness by
polishing is used, the overall thickness of the module with
embedded semiconductor IC can be made extremely thin.
[0014] Preferably, the module with embedded semiconductor IC of the
present invention further comprises a first circuit board wiring
pattern formed on the first resin layer side and a second circuit
board wiring pattern formed on the second resin layer side, the
post electrodes are electrically connected at their one ends to the
first circuit board wiring pattern, and the post electrodes are
electrically connected at their other ends to the second circuit
board wiring pattern. This arrangement makes it possible to
establish electrical connection between opposite surfaces of the
module with embedded semiconductor IC. Moreover, a third circuit
board wiring pattern is preferably formed to be embedded between
the first resin layer and the second resin layer. This enables the
module with embedded semiconductor IC to realize a complicated
wiring pattern.
[0015] A module with embedded semiconductor IC according to another
aspect of the present invention comprises a semiconductor IC formed
on its main surface with stud bumps, a first resin layer formed in
contact with a back surface and at least part of a peripheral
surface of the semiconductor IC, and a second resin layer formed in
at least partial contact with the stud bumps, the first resin layer
and the second resin layer being formed of different materials.
[0016] In this aspect of the present invention, since the first
resin layer and the second resin layer are formed of different
materials, the material of each resin layer can be selected in
accordance with the properties it requires. It is therefore
possible to select a material that is better in physical protective
properties with respect to the semiconductor IC as the material of
the first resin layer and select a material that is better in
electrical properties as the material of the second resin layer.
This makes it possible to achieve both physical protection of the
semiconductor IC and excellent electrical properties.
[0017] Specifically, the material forming the second resin layer
preferably has a higher Q value than the material forming the first
resin layer. Further, the material forming the second resin layer
preferably has a lower dielectric constant than the material
forming the first resin layer. When a material better in electrical
properties is selected as the material forming the second resin
layer in this manner, the semiconductor IC can handle very high
frequency signals because the distributed capacity of the
transmission lines is restrained.
[0018] The mechanical strength of the material forming the first
resin layer is preferably higher than that of the material forming
the second resin layer, the water absorption property of the
material forming the first resin layer is preferably lower than
that of the material forming the second resin layer, and the
adhesive property with respect to the semiconductor IC of the
material forming the first resin layer is preferably higher than
that forming the second resin layer. When a material better in
physical properties is selected as the material forming the first
resin layer in this manner, mechanical breakage, corrosion, and
detachment of the semiconductor IC can be effectively prevented to
enhance the reliability of the module with embedded semiconductor
IC.
[0019] In particular, it is preferable for substantially all of the
back surface of the semiconductor IC to be in contact with the
first resin layer, for substantially all of the main surface of the
semiconductor IC to be in contact with the second resin layer, and
for substantially all of the peripheral surface of the
semiconductor IC to be in contact with the first resin layer. This
makes it possible to achieve both physical protection of the
semiconductor IC and excellent electrical properties on a high
order, because the majority of the main surface of the
semiconductor IC contacts the first resin layer and the stud bumps
contact the second resin layer.
[0020] The method of fabricating the module with embedded
semiconductor IC according to the present invention comprises: a
step of forming post electrodes on a first transfer board; a step
of forming first and second locating portions on a second transfer
board, a step of provisionally attaching a semiconductor IC having
stud bumps to the second transfer board while aligning the stud
bumps with the first locating portions; and a step of using the
first and second transfer boards to press-harden a resin while
using the second locating portions and the post electrodes to align
the first transfer board with the second transfer board.
[0021] According the method of the present invention, the position
of the semiconductor IC stud bumps in the planar direction is
substantially fixed with respect to the position of the post
electrodes in the planar direction. Since this means that
substantially no deviation occurs, it becomes possible to form a
wiring pattern that connects with the stud bumps. As a result, it
is possible to use a semiconductor IC having a very narrow
electrode pitch of 100 .mu.m or smaller, particularly of around 60
.mu.m.
[0022] The method of the present invention preferably further
comprises a step of reducing the thickness of the semiconductor IC
by polishing its back surface before provisionally attaching the
semiconductor IC to the second transfer board. This enables the
overall thickness of the module with embedded semiconductor IC to
be made very thin.
[0023] The method of the present invention preferably further
comprises a step of forming the board wiring pattern on at least
one of the first transfer board and the second transfer board. This
enables the board wiring pattern to be formed simultaneously with
the resin press-hardening step.
[0024] The method of the present invention preferably further
comprises: a step following resin hardening of detaching the second
transfer board to expose the post electrodes and stud bumps; a step
of forming a resin layer covering the exposed post electrodes and
stud bumps; a step of removing part of the resin layer to again
expose the post electrodes and stud bumps; and a step of forming a
board wiring pattern matched to the again exposed post electrodes
and stud bumps. In this case, the position of the stud bumps in the
planar direction and the position of the post electrodes in the
planar direction are substantially fixed. Since this means that
substantially no deviation occurs, it becomes possible to form the
wiring pattern.
[0025] A multilayer substrate can be used as the first transfer
board. In this case, the first transfer board need not be detached
but can be used as it is as a part of the module with embedded
semiconductor IC.
[0026] As explained in the foregoing, the present invention can
provide a module with embedded semiconductor IC that utilizes a
semiconductor IC with a very narrow electrode pitch. In addition,
the present invention enables simultaneous achievement of both good
semiconductor IC physical protection and excellent electrical
properties.
BRIEF DESCRIPTION OF THE DRAWINGS
[0027] The above and other objects, features and advantages of this
invention will become more apparent by reference to the following
detailed description of the invention taken in conjunction with the
accompanying drawings, wherein:
[0028] FIG. 1 is a schematic sectional view showing the structure
of a module with embedded semiconductor IC 100 that is a preferred
embodiment of the present invention.
[0029] FIG. 2 is a schematic sectional view showing the structure
of the semiconductor IC 100.
[0030] FIG. 3 is a diagram showing a part of the fabrication
process of the module with embedded semiconductor IC 100 (formation
of dry films 102 and 103).
[0031] FIG. 4 is a diagram showing another part of the fabrication
process of the module with embedded semiconductor IC 100
(patterning dry film 102).
[0032] FIG. 5 is a diagram showing still another part of the
fabrication process of the module with embedded semiconductor IC
100 (formation of lower board wiring patterns 110 and 111).
[0033] FIG. 6 is a diagram showing still another part of the
fabrication process of the module with embedded semiconductor IC
100 (removing dry films 102 and 103).
[0034] FIG. 7 is a diagram showing still another part of the
fabrication process of the module with embedded semiconductor IC
100 (formation of dry films 104 and 105).
[0035] FIG. 8 is a diagram showing still another part of the
fabrication process of the module with embedded semiconductor IC
100 (patterning dry film 104).
[0036] FIG. 9 is a diagram showing still another part of the
fabrication process of the module with embedded semiconductor IC
100 (formation of post electrodes 120).
[0037] FIG. 10 is a diagram showing still another part of the
fabrication process of the module with embedded semiconductor IC
100 (removing dry films 104 and 105).
[0038] FIG. 11 is a diagram showing still another part of the
fabrication process of the module with embedded semiconductor IC
100 (formation of locating holes 106a and 106b).
[0039] FIG. 12 is a diagram for explaining a positioning method in
the case where a transfer board 106 is provided with locating holes
106a only with respect to some of the stud bumps 132.
[0040] FIG. 13 is a diagram showing still another part of the
fabrication process of the module with embedded semiconductor IC
100 (provisional attachment of semiconductor IC 130).
[0041] FIG. 14 is a diagram showing still another part of the
fabrication process of the module with embedded semiconductor IC
100 (pressing by transfer boards 101 and 106).
[0042] FIG. 15 is a diagram showing still another part of the
fabrication process of the module with embedded semiconductor IC
100 (formation of resin layer 140).
[0043] FIG. 16 is a diagram showing still another part of the
fabrication process of the module with embedded semiconductor IC
100 (removing transfer boards 101 and 106).
[0044] FIG. 17 is a diagram showing still another part of the
fabrication process of the module with embedded semiconductor IC
100 (formation of prepreg 150a).
[0045] FIG. 18 is a diagram showing still another part of the
fabrication process of the module with embedded semiconductor IC
100 (formation of resin layer 150).
[0046] FIG. 19 is a diagram showing still another part of the
fabrication process of the module with embedded semiconductor IC
100 (formation of under conductor layer 160).
[0047] FIG. 20 is a diagram showing still another part of the
fabrication process of the module with embedded semiconductor IC
100 (formation of dry films 107 and 108).
[0048] FIG. 21 is a diagram showing still another part of the
fabrication process of the module with embedded semiconductor IC
100 (patterning dry film 107).
[0049] FIG. 22 is a diagram showing still another part of the
fabrication process of the module with embedded semiconductor IC
100 (formation of upper board wiring patterns 170 and 171).
[0050] FIG. 23 is a diagram showing still another part of the
fabrication process of the module with embedded semiconductor IC
100 (removing dry films 107 and 108).
[0051] FIG. 24 is a diagram showing still another part of the
fabrication process of the module with embedded semiconductor IC
100 (removing under conductor layer 160).
[0052] FIG. 25 is a diagram showing a part of another fabrication
process of the module with embedded semiconductor IC 100 (formation
of holes 151).
[0053] FIG. 26 is a diagram showing another part of the fabrication
process of the module with embedded semiconductor IC 100 (formation
of under conductor layer 160).
[0054] FIG. 27 is a diagram showing still another part of the
fabrication process of the module with embedded semiconductor IC
100 (removing dry films 107 and 108).
[0055] FIG. 28 is a diagram showing still another part of the
fabrication process of the module with embedded semiconductor IC
100 (patterning dry film 107).
[0056] FIG. 29 is a diagram showing still another part of the
fabrication process of the module with embedded semiconductor IC
100 (formation of upper board wiring patterns 170 and 171).
[0057] FIG. 30 is a diagram showing still another part of the
fabrication process of the module with embedded semiconductor IC
100 (removing dry films 107 and 108).
[0058] FIG. 31 is a diagram showing still another part of the
fabrication process of the module with embedded semiconductor IC
100 (removing under conductor layer 160).
[0059] FIG. 32 is a schematic sectional view showing the structure
of a module with embedded semiconductor IC 200 that is another
preferred embodiment of the present invention.
[0060] FIG. 33 is a diagram showing a part of the fabrication
process of the module with embedded semiconductor IC 200 (formation
of locating holes 201a and 201b).
[0061] FIG. 34 is a diagram showing another part of the fabrication
process of the module with embedded semiconductor IC 200 (formation
of dry films 202 and 203).
[0062] FIG. 35 is a diagram showing still another part of the
fabrication process of the module with embedded semiconductor IC
200 (patterning dry film 203).
[0063] FIG. 36 is a diagram showing still another part of the
fabrication process of the module with embedded semiconductor IC
200 (formation of internal board wiring pattern 290).
[0064] FIG. 37 is a diagram showing still another part of the
fabrication process of the module with embedded semiconductor IC
200 (removing dry films 202 and 203).
[0065] FIG. 38 is a diagram showing still another part of the
fabrication process of the module with embedded semiconductor IC
200 (provisional attachment of semiconductor IC 230).
[0066] FIG. 39 is a diagram showing still another part of the
fabrication process of the module with embedded semiconductor IC
200 (pressing by transfer boards 201 and 206).
[0067] FIG. 40 is a diagram showing still another part of the
fabrication process of the module with embedded semiconductor IC
200 (formation of resin layer 240).
[0068] FIG. 41 is a diagram showing still another part of the
fabrication process of the module with embedded semiconductor IC
200 (removing transfer boards 201 and 206).
[0069] FIG. 42 is a diagram showing still another part of the
fabrication process of the module with embedded semiconductor IC
200 (formation of prepreg 250a).
[0070] FIG. 43 is a diagram showing still another part of the
fabrication process of the module with embedded semiconductor IC
200 (formation of resin layer 250).
[0071] FIG. 44 is a diagram showing still another part of the
fabrication process of the module with embedded semiconductor IC
200 (formation of under conductor layers 260 and 261).
[0072] FIG. 45 is a diagram showing still another part of the
fabrication process of the module with embedded semiconductor IC
200 (formation of dry films 207 and 208).
[0073] FIG. 46 is a diagram showing still another part of the
fabrication process of the module with embedded semiconductor IC
200 (patterning dry films 207 and 208).
[0074] FIG. 47 is a diagram showing still another part of the
fabrication process of the module with embedded semiconductor IC
200 (formation of upper board wiring patterns 270 and 271 and lower
board wiring patterns 210 and 211).
[0075] FIG. 48 is a diagram showing still another part of the
fabrication process of the module with embedded semiconductor IC
200 (removing dry films 207 and 208).
[0076] FIG. 49 is a diagram showing still another part of the
fabrication process of the module with embedded semiconductor IC
200 (removing under conductor layers 260 and 261).
[0077] FIG. 50 is a schematic sectional view showing an example in
which the interface between the resin layer 140 and resin layer 150
is located below the main surface 130a of the semiconductor IC
130.
[0078] FIG. 51 is a schematic sectional view showing an example in
which the interface between the resin layer 140 and resin layer 150
is located above the main surface 130a of the semiconductor IC
130.
DETAILED DESCRIPTION OF THE EMBODIMENTS
[0079] Preferred embodiments of the present invention will now be
explained in detail with reference to the drawings.
[0080] FIG. 1 is a schematic sectional view showing the structure
of a module with embedded semiconductor IC 100 that is a preferred
embodiment of the present invention.
[0081] As shown in FIG. 1, the module with embedded semiconductor
IC 100 of this embodiment has a laminated resin layer 140 (first
resin layer) and resin layer 150 (second resin layer), a
semiconductor IC 130 embedded between the resin layer 140 and resin
layer 150, lower board wiring patterns 110, 111 (together
constituting a first circuit board wiring pattern) formed as
embedded in the surface of the resin layer 140, upper board wiring
patterns 170, 171 (together constituting a second circuit board
wiring pattern) formed on the surface of the resin layer 150, an
under conductor layer 160 formed under the upper board wiring
patterns 170, 171, post electrodes 120 formed as embedded in and
passing through the resin layer 140 and resin layer 150 to
electrically connect the lower board wiring pattern 111 and the
upper board wiring pattern 171, a protective layer 180 covering the
surface of the resin layer 140 and the lower board wiring patterns
110, 111, and a protective layer 181 covering the surface of the
resin layer 150 and the upper board wiring patterns 170, 171. The
land electrodes of the semiconductor IC 130 (not shown in FIG. 1)
are formed thereon with stud bumps 132 and the land electrodes are
electrically connected to the upper board wiring pattern 170
through the stud bumps 132. As shown in FIG. 1, the stud bumps 132
pass through the resin layer 150.
[0082] Although not shown in FIG. 1, capacitors and other such
passive components are mounted on the surfaces of the protective
layers 180, 181 and are electrically connected to the lower board
wiring patterns 110, 111 or the upper board wiring patterns 170,
171 through via holes (BVH) formed in the protective layers 180,
181.
[0083] The semiconductor IC 130 incorporated in the module with
embedded semiconductor IC 100 of this embodiment is one that has
been reduced in thickness by polishing. As a result, the overall
thickness of the module with embedded semiconductor IC 100 can be
reduced to under 1 mm, e.g., to around 200 .mu.m. Moreover, as
explained in further detail later, the position of the
semiconductor IC 130 stud bumps 132 in the planar direction is
substantially fixed with respect to the position of the post
electrodes 120 in the planar direction. Therefore, substantially no
shift in the positional relationship between the stud bumps 132 and
the upper board wiring pattern 170 occurs in the course of
fabrication.
[0084] FIG. 2 is a schematic sectional view showing the structure
of the semiconductor IC 130.
[0085] As shown in FIG. 2, the semiconductor IC 130 is a bare chip
semiconductor IC whose main surface 130a is formed with numerous
land electrodes 131 (only four shown) The pitch of the land
electrodes 131 (electrode pitch) is not particularly specified but
can be very fine owing to the fact that substantially no shift
arises in the positional relationship between the land electrodes
131 and the upper board wiring pattern 170 in the module with
embedded semiconductor IC 100 of this embodiment. Therefore, a
semiconductor IC with a very narrow electrode pitch of 100 .mu.m or
smaller, for instance, 60 .mu.m, can be used.
[0086] Moreover, the back surface 130b of the semiconductor IC 130
is polished to make the thickness t of the semiconductor IC 130
(distance from the main surface 130a to the back surface 130b) much
thinner than the thickness of an ordinary semiconductor IC.
Although the thickness t is not particularly specified, it is
preferably set at 200 .mu.m or less, for example, 20-50 .mu.m. The
polishing of the back surface 130b is preferably conducted
simultaneously with respect to a large number of semiconductor ICs
in the wafer state, followed by dicing for separating them into
individual semiconductor ICs 130. When the dicing into the
individual semiconductor ICs 130 is done before thickness reduction
by polishing, the operation can be efficiently conducted by
polishing the back surface 130b with the main surface 130a of the
semiconductor IC 130 in a covered state.
[0087] Each land electrode 131 is formed with a stud bump 132. The
size of the stud bumps 132 can be appropriately decided based on
the electrode pitch. If the electrode pitch is about 100 .mu.m, for
example, it would be appropriate to set the stud bump diameter at
30-50 .mu.m and height at 40-80 .mu.m. The stud bumps 132 can be
formed on the land electrodes 131 of the individual semiconductor
ICs 130 after dicing by use of a wire bonder. While other
possibilities also exist, the material used for the stud bumps 132
is preferably copper (Cu). Use of copper (Cu) as the material of
the stud bumps 132 enhances reliability compared with the case of
using gold (Au) because stronger bonding strength with the land
electrodes 131 can be realized.
[0088] As shown in FIG. 1, in the module with embedded
semiconductor IC 100 of this embodiment, the back surface 130b and
peripheral surface 130c of the semiconductor IC 130 are in contact
with the resin layer 140, while the main surface 130a of the
semiconductor IC 130 is in contact with the resin layer 150. As a
result, the majority of the surface area of the semiconductor IC
130 is in contact with the resin layer 140 and the stud bumps 132
are in contact with the resin layer 150.
[0089] The resin layer 140 and the resin layer 150 are preferably
formed of different materials. Specifically, a material better in
physical protective properties with respect to the semiconductor IC
130 is preferable as the resin layer 140 material and a material
better in electrical properties is preferably selected as the resin
layer 150 material.
[0090] Materials better in physical protective properties with
respect to the semiconductor IC 130 are ones having high mechanical
strength, low water absorption property and high adhesive property
with respect to the semiconductor IC 130. Since, as set out in the
foregoing, the resin layer 140 is in contact with the majority of
the surface area of the semiconductor IC 130, selection of a
material having such properties as the material of the resin layer
140 makes it possible to effectively protect the semiconductor IC
130 against mechanical breakage, corrosion, detachment and the
like, and thus realize enhanced reliability. Materials meeting this
description include, but are not limited to, epoxy resin, phenol
resin and benzoxazine resin, any of these resins added with talc,
calcium carbonate, magnesium carbonate, aluminum hydroxide,
magnesium hydroxide, aluminum borate whiskers, potassium titanate
fiber, glass flakes, glass fiber, tantalum nitride, aluminum
nitride or the like, any of these resins added with a metal oxide
powder containing at least one metal selected from the group
composed of magnesium, silicon, titanium, zinc, calcium, strontium,
zirconia, tin, niobium, samarium, bismuth, aluminum, lead,
lanthanum, lithium and tantalum, any of these resins blended with a
resin fiber such as aramid fiber or the like, and any of these
resins impregnated with glass cloth, aramid fiber, non-woven fabric
or the like. Although these materials offer excellent physical
protection of the semiconductor IC 130, they are not so good in
electrical properties. This is not a problem, however, because the
resin layer 140 is not in contact with the stud bumps 132.
[0091] Although no specific range is set for the mechanical
strength of the resin layer 140, it preferably has a bending
strength of not less than 100 MPa, more preferably not less than
120 MPa. A resin layer 140 having a bending strength of this
magnitude ensures effective protection of the semiconductor IC 130
against mechanical breakage, corrosion, detachment and the like,
thus enhancing the reliability of the module with embedded
semiconductor IC 100.
[0092] Although no specific range is set for the water absorption
of the resin layer 140, the water absorption value of the resin
layer 140 after a 24-hour accelerated test conducted at a
temperature of 121.degree. C. and relative humidity of 100% is
preferably not greater than 1.0%, more preferably not greater than
0.6%. A resin layer 140 satisfying these values effectively
restrains expansion of the resin layer 140, especially after
reflow.
[0093] Although the adhesive property of the resin layer 140 with
respect to semiconductor IC 130 is not particularly defined, the
adhesive property is preferably of a level such that, in the
fabrication process set out later, no visible bubbles remain at the
interface between the resin layer 140 and semiconductor IC 130.
[0094] Materials better in electrical properties are ones having
high Q value and ones having low dielectric constant. Since, as
explained in the foregoing, the resin layer 150 makes contact with
the stud bumps 132, selection of a material having such properties
as the material for resin layer 150 makes it possible to restrain
the distributed capacity of the transmission lines, thus enabling
the semiconductor IC 130 to handle very high frequency signals. The
dielectric constant of the resin layer 150 is preferably lower than
that of the material better in mechanical protection of the
semiconductor IC 130 by at least 0.2, more preferably by at least
0.5. The dielectric constant of epoxy resin, the material generally
used in printed circuit boards, is around 4.5. If the dielectric
constant of the resin layer 150 is 0.2 or more below this value,
the distributed capacity can be lowered by around 5%, and if it is
0.5 or more lower, the distributed capacity can be reduced by
around 10%. The Q value of the resin layer 150 is preferably 100 or
greater, more preferably 300 or greater. When a coil is fabricated
on a printed circuit board whose material has Q value below 100,
the f-Q characteristic of the coil is markedly affected to the
point that the coil cannot achieve an adequate Q value. When a coil
having an especially high Q value is required, such as in a PA
(power amplifier) or VCO (voltage-controlled oscillator), the Q
value of the material needs to be 300 or greater, because at a
lower value it is not possible to attain the generally required
characteristics.
[0095] Materials meeting these requirements include, but are not
limited to, poly(vinyl benzyl ether) compound resin,
bismaleimdetriazine resin (BT resin), cyanate ester resin,
epoxy+activated ester curing resin, polyphenylene ether resin
(polyphenylene oxide resin), curable polyolefin resin,
benzocyclobutene resin, polyamide resin, aromatic liquid crystal
polyester resin, polyphenylene sulfide resin, polyether amide
resin, poly (etheretherketone) resin and fluororesin, any of these
resins added with silica, talc, calcium carbonate, magnesium
carbonate, aluminum hydroxide, magnesium hydroxide, aluminum borate
whiskers, potassium titanate fiber, alumina glass flakes, glass
fiber, tantalum nitride, aluminum nitride or the like, any of these
resins added with a metal oxide powder containing at least one
metal selected from the group composed of magnesium, silicon,
titanium, zinc, calcium, strontium, zirconia, tin, niobium,
samarium, aluminum, bismuth, lead, lanthanum, lithium and tantalum,
any of these resins blended with a resin fiber such as aramid fiber
or the like, and any of these resins impregnated with glass cloth,
aramid fiber, non-woven fabric or the like. Although these
materials offer excellent electrical properties, they are not so
good in physical protection properties with respect to the
semiconductor IC 130. This is not a problem, however, because the
area of contact of the resin layer 150 with the semiconductor IC
130 is relatively small.
[0096] A method of fabricating the module with embedded
semiconductor IC 100 shown in FIG. 1 will now be explained with
reference to the drawings.
[0097] FIGS. 3 to 24 are process diagrams for explaining the method
of fabricating the module with embedded semiconductor IC 100 shown
in FIG. 1.
[0098] First, a transfer board 101 (the first transfer board) is
prepared and photosensitive dry films 102 and 103 are attached to
the face 101a and underside 101b thereof (FIG. 3). The transfer
board 101 can be made of any material that is electrically
conductive. However, in view of the fact that it is peeled off in a
later processing step, it is preferably made of a material having
low adhesive property with respect to the resin layer 140 shown in
FIG. 1. Materials that adhere weakly to resin include nickel (Ni)
and stainless steel. The thickness of the transfer board 101 is not
particularly defined except that it must be sufficient to ensure
the mechanical strength it requires. A thickness of 50 .mu.m is
satisfactory, for example. The thickness of the dry film 102 must
be made somewhat greater than that of the lower board wiring
patterns 110 and 111. When the thickness of the lower board wiring
patterns 110 and 111 are about 20 .mu.m, for instance, the
thickness of the dry film 102 should be made about 25 .mu.m. As
will be explained further later, the dry film 103 is provided for
the purpose of preventing electroplating of the underside 101b of
the transfer board 101 and can be of any desired thickness.
[0099] Next, the dry film 102 is exposed using a photomask (not
shown) and the dry film 102 is removed at the regions 110a and 111a
where the lower board wiring patterns 110 and 111 are to be formed
(FIG. 4). This exposes the face 101a of the transfer board 101 at
the regions 110a and 111a. As the dry film 103 is not removed at
this time, the underside 101b of the transfer board 101 remains
covered substantially throughout.
[0100] After portions of the face 101a of the transfer board 101
have been removed in this manner, electroplating is conducted with
the transfer board 101 as the substrate. This forms the lower board
wiring patterns 110 and 111 at the exposed regions 110a and 111a,
respectively, of the transfer board 101 (FIG. 5). The underside
101b of the transfer board 101 is not electroplated because it is
substantially totally covered by the dry film 103. The type of
plating solution can be appropriately selected in accordance with
the desired material of the lower board wiring patterns 110 and
111. When the lower board wiring patterns 110 and 111 are to be
made of copper (Cu), for example, copper sulfate can be used as the
plating solution. The dry films 102 and 103 are then peeled off to
obtain the transfer board 101 with the lower board wiring patterns
110 and 111 formed on its face 101a (FIG. 6).
[0101] Next, another set of dry films 104 and 105 are attached to
the face 101a and underside 101b of the transfer board 101 (FIG.
7). The thickness of the dry film 104 needs to be made somewhat
thicker than that of the post electrodes 120. When the thickness of
the post electrodes 120 is about 90 .mu.m, for instance, the
thickness of the dry film 104 should be made about 100 .mu.m. Like
the dry film 103, the dry film 105 is provided for the purpose of
preventing electroplating of the underside 101b of the transfer
board 101 and can be of any desired thickness.
[0102] Next, the dry film 104 is exposed using a photomask (not
shown) and the dry film 104 is removed at the regions 120a where
the post electrodes 120 are to be formed (FIG. 8). As shown in FIG.
8, the regions 120a where the post electrodes 120 are to be formed
are regions located at about the middle of the regions constituting
the lower board wiring pattern 111. This local exposure and removal
of the dry film 104 exposes the lower board wiring pattern 111 at
the regions 120a. As the dry film 105 is not removed at this time,
the underside 101b of the transfer board 101 remains covered
substantially throughout.
[0103] After portions of the lower board wiring pattern 111 have
been exposed in this manner, electroplating is conducted with the
transfer board 101 as the substrate. This forms the post electrodes
120 at the exposed regions 120a of the lower board wiring pattern
111 (FIG. 9). The underside 101b of the transfer board 101 is not
electroplated because its surface is substantially totally covered
by the dry film 105. The type of plating solution used, which is
selected as explained earlier, can be copper sulfate. The dry films
104 and 105 are then peeled off to obtain the transfer board 101
with the lower board wiring patterns 110, 111 and the post
electrodes 120 formed on its face 101a (FIG. 10). This completes
the processing of the transfer board 101.
[0104] Next, another transfer board 106 (the second transfer board)
is prepared separately of the transfer board 101 and etched at
prescribed regions using an etching mask (not shown) to form
locating holes 106a (the first locating portions) and locating
holes 106b (the second locating portions) (FIG. 11). The transfer
board 106 can be made of the same material and given the same
thickness as the transfer board 101 but, differently from the
transfer board 101, it is not required to be electrically
conductive. In view of the fact that it is peeled off in a later
processing step, however, it is preferably made of a material
having low adhesive property with respect to the resin layer 140.
When the transfer board 106 is made of the same material as the
transfer board 101, the locating holes 106a, 106b can be formed by
wet etching using ferric chloride.
[0105] In a later processing step, the stud bumps 132 are inserted
into the locating holes 106a so as to provisionally attach the
semiconductor IC 130 to the transfer board 106 in a positioned
state. The diameter of the locating holes 106a is therefore made
about the same size as or slightly larger than that of the stud
bumps 132. The diameter of the locating holes 106a should not be
set larger than necessary because, when too large relative to the
diameter of the stud bumps 132, the semiconductor IC 130 cannot be
provisionally attached to the transfer board 106. The number of the
locating holes 106a formed can be fewer than the number of stud
bumps 132 so long as the semiconductor IC 130 can nevertheless be
provisionally attached to the transfer board 106. Specifically, as
shown in FIG. 12, a structure can be adopted wherein locating holes
106a are formed for only some of the stud bumps 132 and regions
corresponding to the remaining stud bumps 132 are formed with slots
106c of a size considerably larger than the diameter of the stud
bumps 132 so that interference between the remaining stud bumps 132
and the transfer board 106 is avoided.
[0106] In another processing step conducted later, the post
electrodes 120 are inserted into the locating holes 106b so as to
position the transfer board 106 with respect to the transfer board
101. The diameter of the locating holes 106b therefore needs to be
made slightly larger than that of the post electrodes 120. However,
the diameter of the locating holes 106b should not be set larger
than necessary because, when too large relative to the diameter of
the post electrodes 120, the accuracy of the positioning is
reduced.
[0107] Thus the locating holes 106a and locating holes 106b formed
in the transfer board 106 are holes for insertion of the stud bumps
132 and post electrodes 120 in later processing steps. Since the
relative positions among these holes is therefore a critical factor
in determining accuracy, they must be formed with high accuracy.
Insofar as the required processing accuracy can be ensured, it is
possible to form the locating holes 106a and 106b by some other
method, such as by drilling. This completes the processing of the
transfer board 106.
[0108] The semiconductor IC 130 is also processed, separately from
the processing carried out on the transfer board 101 and transfer
board 106. As explained earlier, the processing with respect to the
semiconductor IC 130 is of two types: thickness reduction by
polishing and formation of the stud bumps 132. As was also pointed
out earlier, the polishing for thickness reduction can be conducted
by polishing the back surface 130b of numerous semiconductors ICs
130 in the wafer state to reduce the thickness t to 200 .mu.m or
less, e.g., to 20-50 .mu.m, followed by dicing for separating them
into individual semiconductor ICs 130. A wire bonder can be used to
form the stud bumps 132 on the land electrodes 131 of the
individual semiconductor ICs 130 after separation by dicing. By
this there can be fabricated a semiconductor IC 130 such as shown
in FIG. 2 that is reduced in thickness and formed on its land
electrodes 131 with stud bumps 132.
[0109] Upon completion of the processing of the transfer board 106
and the semiconductor IC 130, the stud bumps 132 of the
semiconductor IC 130 are inserted into the locating holes 106a
formed in the transfer board 106, thereby provisionally attaching
the semiconductor IC 130 to the transfer board 106 (FIG. 13). This
positions the semiconductor IC 130 on the transfer board 106.
[0110] Next, a prepreg 140a is pressed between the transfer board
101 and transfer board 106 while positioning the transfer board 106
with respect to the transfer board 101, so as to insert the post
electrodes 120 into the locating holes 106b formed in the transfer
board 106 (FIG. 14). The prepreg 140a is a sheet obtained by
impregnating carbon fiber, glass fiber, aramid fiber or other such
fiber with epoxy or other unhardened thermosetting resin having
high mechanical strength, low water absorption property and high
adhesive property with respect to the semiconductor IC 130. When
the prepreg 140a is pressed with heating, the thermosetting resin
therein hardens to form the resin layer 140 (FIG. 15). As a result,
the lower board wiring pattern 110 and lower board wiring pattern
111, post electrodes 120 and semiconductor IC 130 are united by the
resin layer 140 and the back surface 130b and peripheral surface
130c of the semiconductor IC 130 are covered by the resin layer
140. The main surface 130a of the semiconductor IC 130 is not
covered by the resin layer 140 and remains exposed. The transfer
board 101 and transfer board 106 are then peeled off to obtain a
unitary laminated body (FIG. 16). As shown in FIG. 16, after the
transfer board 101 and transfer board 106 have been peeled off, the
post electrodes 120 and stud bumps 132 are in a protruding state.
The planar positional relationship between the post electrodes 120
and stud bumps 132 coincides substantially with the planar
positional relationship between the locating holes 106a and
locating holes 106b formed in the transfer board 106. The
positional relationship between the two is therefore substantially
fixed.
[0111] The surface from which the post electrodes 120 and stud
bumps 132 protrude is then overlaid with a prepreg 150a so as to
completely cover the protruding post electrodes 120 and stud bumps
132 (FIG. 17). The prepreg 150a used is preferably made of a
different material from that of the prepreg 140a used to form the
resin layer 140. Specifically, it is preferably made of a material
high in Q value and low in dielectric constant, such as a material
obtained by blending a filler into a poly(vinyl benzyl ether)
compound resin. The prepreg 150a is hardened by application of heat
to form the resin layer 150, whereafter the surface region thereof
is removed by grinding or blasting to expose the post electrodes
120 and stud bumps 132 (FIG. 18).
[0112] Next, a sputtering or other such vapor phase growth method
is used to form an under conductor layer 160 completely covering
the surface on the side where the post electrodes 120 and stud
bumps 132 are exposed (FIG. 19). The method of forming the under
conductor layer 160 is not limited to the vapor phase growth
method. It can instead be formed by plating or by attaching a metal
foil. Since unnecessary portions of the under conductor layer 160
are later removed, the thickness of the under conductor layer 160
needs to be set sufficiently thin, at around 0.3 .mu.m, for
example.
[0113] Next, photosensitive dry films 107 and 108 are attached to
the surfaces of the laminated body, i.e., to the surface of the
resin layer 140 and the surface of the under conductor layer 160
(FIG. 20). The thickness of the dry film 107 needs to be made
somewhat thicker than the upper board wiring patterns 170 and 171.
For example, when the thickness of the upper board wiring patterns
170 and 171 is about 20 .mu.m, the thickness of the dry film 107
should be made about 25 .mu.m. The dry film 108 is provided for the
purpose of preventing electroplating of the surface of the resin
layer 140 formed with the lower board wiring patterns 110 and 111
and can be of any desired thickness.
[0114] Next, the dry film 107 is exposed using a photomask (not
shown) and the dry film 107 is removed at the regions 170a and 171a
where the upper board wiring patterns 170 and 171 are to be formed
(FIG. 21). This exposes the under conductor layer 160 at the
regions 170a and regions 171a. As the dry film 108 is not removed
at this time, the surface of the resin layer 140 formed with the
lower board wiring patterns 110 and 111 remains covered
substantially throughout.
[0115] As shown in FIG. 21, the regions 170a where the upper board
wiring pattern 170 is to be formed include regions lying opposite
the stud bumps 132. Since, as was explained earlier, a
semiconductor IC 130 having a very narrow electrode pitch is used
in this embodiment, a large planar direction shift in the
positional relationship between the stud bumps 132 and the regions
170a cannot not be tolerated. However, as was also pointed out
earlier, the positional relationship in the planar direction of the
stud bumps 132 and the post electrodes 120 is substantially fixed.
This means that the positional relationship between the photomask
pattern corresponding to the regions 170a and the photomask pattern
corresponding to the regions 171a substantially coincide with the
positional relation in the planar direction between the stud bumps
132 and the post electrodes 120. The regions of the under conductor
layer 160 corresponding to the stud bumps 132 can therefore be
accurately exposed.
[0116] After portions of the under conductor layer 160 have been
exposed in this manner, electroplating is conducted with the under
conductor layer 160 as the substrate. This forms the upper board
wiring patterns 170 and 171 at the regions 170a and 171a where the
under conductor layer 160 is exposed (FIG. 22). The surface of the
resin layer 140 is not electroplated because substantially its
total surface is covered by the dry film 108. The type of plating
solution used, which is selected as explained earlier, can be
copper sulfate. The dry films 107 and 108 are then peeled off to
obtain a laminated body having the upper board wiring patterns 170
and 171 formed on the surface of the under conductor layer 160
(FIG. 23).
[0117] An etchant such as an acid is then used to remove (by soft
etching) the unnecessary under conductor layer 160 at portions
where the upper board wiring patterns 170 and 171 are not formed
(FIG. 24). Next, the surfaces of the laminated body are covered
with the photosensitive protective layers 180 and 181, which are
then removed at portions corresponding to the regions where
capacitors and other passive components are to be mounted, thereby
exposing portions of the lower board wiring pattern 110 and upper
board wiring pattern 170. Finally, the passive components are
mounted to complete the module with embedded semiconductor IC 100
shown in FIG. 1.
[0118] As explained in the foregoing, the transfer board 106 having
the locating holes 106a and 106b is used to fabricate the module
with embedded semiconductor IC 100 of this embodiment. The
positional relationship between the stud bumps 132 and post
electrodes 120 in the planar direction is therefore substantially
fixed. As a result, the positional relationship between photomask
pattern corresponding to the regions 170a and the photomask pattern
corresponding to the regions 171a substantially coincides with the
positional relationship between the stud bumps 132 and the post
electrodes 120 in the planar direction. From this it follows that,
at the time of forming the upper board wiring patterns 170 and 171,
accurate registration with respect to the stud bumps 132 can be
achieved. Therefore, even if a semiconductor IC 130 having a very
narrow electrode pitch of 100 .mu.m or smaller, e.g., 60 .mu.m, is
used, deviation in the positional relationship between the land
electrodes 131/stud bumps 132 and the upper board wiring pattern
170 can be held to the minimum.
[0119] In addition, since the semiconductor IC 130 used in this
embodiment is polished down to a very small thickness t, the module
with embedded semiconductor IC 100 can be obtained at a very thin
thickness of, for example, around 200 .mu.m.
[0120] In the method of fabrication described in the foregoing, the
formation of the resin layer 150 is followed by grinding or
blasting of its surface to expose the post electrodes 120 and stud
bumps 132 (see FIG. 18). However, the exposure of the post
electrodes 120 and stud bumps 132 can instead be achieved by using
a laser or the like to form holes. This method will now be
explained with reference to the drawings.
[0121] FIGS. 25 to 31 are process diagrams for explaining a method
of fabrication in the case where the post electrodes 120 and stud
bumps 132 are exposed by forming holes.
[0122] After the fabrication process has been completed through the
step illustrated in FIG. 17, a laser beam is irradiated onto the
regions corresponding to the post electrodes 120 and stud bumps 132
to form holes 151 in the resin layer 150 and thus expose the post
electrodes 120 and stud bumps 132 (FIG. 25). It is also possible to
form the holes 151 by a method other than laser irradiation.
[0123] The remaining processes are similar to those shown in FIG.
19 onward. Specifically, the thin under conductor layer 160 is
formed to completely cover the surface on the side where the post
electrodes 120 and stud bumps 132 are exposed (FIG. 26), the
photosensitive dry films 107, 108 are attached to the surfaces of
the laminated body (FIG. 27), the dry film 107 is exposed using a
photomask (not shown), and the dry film 107 is removed at the
regions 170a, 171a (FIG. 28). Next, electroplating is conducted
with the under conductor layer 160 as the substrate, thereby
forming the upper board wiring patterns 170 and 171 at the regions
170a and 171a, respectively (FIG. 29). Following this, the dry
films 107 and 108 are peeled off (FIG. 30) and the unnecessary
under conductor layer 160 at portions where the upper board wiring
patterns 170 and 171 are not formed is removed (by soft etching)
(FIG. 31). Next, the surfaces of the laminated body are covered
with the photosensitive protective layers 180 and 181, which are
then removed at portions corresponding to the regions where
capacitors and other passive components are to be mounted, thereby
exposing portions of the lower board wiring pattern 110 and upper
board wiring pattern 170. Finally, the passive components are
mounted to complete the module with embedded semiconductor IC.
[0124] A module with embedded semiconductor IC that is another
embodiment of the present invention will be explained.
[0125] FIG. 32 is a schematic sectional view showing the structure
of a module with embedded semiconductor IC 200 that is another
preferred embodiment of the present invention.
[0126] As shown in FIG. 32, the module with embedded semiconductor
IC 200 of this embodiment has a laminated resin layer 240 and resin
layer 250, a semiconductor IC 230 and an internal board wiring
pattern 290 (third circuit board wiring pattern) embedded between
the resin layer 240 and resin layer 250, lower board wiring
patterns 210, 211 formed on the surface of the resin layer 240,
upper board wiring patterns 270, 271 formed on the surface of the
resin layer 250, an under conductor layer 261 formed on resin layer
240 side of the lower board wiring patterns 210, 211, an under
conductor layer 260 formed on the resin layer 250 side of the upper
board wiring patterns 270, 271, post electrodes 220 formed as
embedded in and passing through the resin layer 240 and resin layer
250 to electrically connect the lower board wiring pattern 211 and
the upper board wiring pattern 271, a protective layer 280 covering
the surface of the resin layer 240 and the lower board wiring
patterns 210, 211, and a protective layer 281 covering the surface
of the resin layer 250 and the upper board wiring patterns 270,
271. Thus the module with embedded semiconductor IC 200 according
to this embodiment differs from the module with embedded
semiconductor IC 100 described earlier chiefly in the point that it
is provided with the internal board wiring pattern 290 and the
point that the lower board wiring patterns 210 and 211 are not
embedded in the resin layer 240 but formed on the surface
thereof.
[0127] The module with embedded semiconductor IC 200 according to
this embodiment also has capacitors and other such passive
components that are mounted on the surfaces of the protective
layers 280 and 281 and are electrically connected to the lower
board wiring patterns 210 and 211 or the upper board wiring
patterns 270 and 271 through via holes (BVH) formed in the
protective layers 280 and 281. As shown in FIG. 32, the embedded
semiconductor IC 230, which can be of the same type as the
semiconductor IC 130 used in the module with embedded semiconductor
IC 100, is electrically connected to the upper board wiring pattern
270 through stud bumps 232.
[0128] Also in the module with embedded semiconductor IC 200 of
this embodiment, the back surface 230b and peripheral surface 230c
of the semiconductor IC 230 are in contact with the resin layer
240, while the main surface 230a of the semiconductor IC 230 is in
contact with the resin layer 250. As a result, the majority of the
surface area of the semiconductor IC 230 is in contact with the
resin layer 240 and the stud bumps 232 are in contact with the
resin layer 250. The resin layer 240 is a layer similar to the
resin layer 140 of the module with embedded semiconductor IC 100
described earlier and is formed of a material good in physical
protective properties with respect to the semiconductor IC 230. The
resin layer 250 is a layer similar to the resin layer 150 of the
module with embedded semiconductor IC 100 and is formed of a
material good in electrical properties.
[0129] A method of fabricating the module with embedded
semiconductor IC 200 shown in FIG. 32 will now be explained with
reference to the drawings.
[0130] FIGS. 33 to 49 are process diagrams for explaining the
method of fabricating the module with embedded semiconductor IC 200
shown in FIG. 32.
[0131] First, a transfer board 201 is prepared and prescribed
regions thereof are removed by etching using an etching mask (not
shown) to form locating holes 201a and locating holes 201b (FIG.
33). The transfer board 201 can be made of the same material and
given the same thickness as the transfer board 101 of the foregoing
embodiment and the locating holes 201a, 201b can be formed by the
method used to form the locating holes 106a, 106b of the transfer
board 106.
[0132] In a later processing step, the stud bumps 232 are inserted
into the locating holes 201a so as to provisionally attach the
semiconductor IC 230 to the transfer board 201 in a positioned
state. The diameter of the locating holes 201a therefore needs to
be made about the same size as or slightly larger than that of the
stud bumps 232. As was explained with reference to FIG. 12, a
structure can be adopted wherein locating holes 201a are formed for
only some of the stud bumps 232 and regions corresponding to the
remaining stud bumps 232 are formed with slots of a size
considerably larger than the diameter of the stud bumps 232 so that
interference between the remaining stud bumps 232 and the transfer
board 201 is avoided. In another processing step conducted later,
the post electrodes 220 are inserted into the locating holes 201b
so as to position the transfer board 201 with respect to a transfer
board 206 discussed later.
[0133] Next, photosensitive dry films 202 and 203 are attached to
the surfaces of the transfer board 206 (FIG. 34) and the dry film
203 is exposed using a photomask (not shown) to remove the dry film
203 at regions 290a where the internal board wiring pattern 290 is
to be formed (FIG. 35). The dry film 202 is not removed at this
time.
[0134] After portions of underside of the transfer board 201 have
been exposed in this manner, electroplating is conducted with the
transfer board 201 as the substrate. This forms the internal board
wiring pattern 290 at the regions 290a (FIG. 36). The dry films 202
and 203 are then peeled off to obtain the transfer board 201 with
the internal board wiring pattern 290 formed on its underside (FIG.
37).
[0135] Next, the stud bumps 232 of the semiconductor IC 230 having
the same structure as the semiconductor IC 130 of the earlier
embodiment are inserted into the locating holes 201a formed in the
transfer board 201, thereby provisionally attaching the
semiconductor IC 230 to the transfer board 201 (FIG. 38). This
positions the semiconductor IC 230 on the transfer board 201.
[0136] Another transfer board 206 is prepared separately of the
transfer board 201. The post electrodes 220 are formed on the
surface of the transfer board 206 by the same method as used to
form the internal board wiring pattern 290 on the transfer board
201. Next, a prepreg 240a is pressed between the transfer board 201
and transfer board 206 while positioning the transfer board 201
with respect to the transfer board 206 so as to insert the post
electrodes 220 into the locating holes 201b formed in the transfer
board 201 (FIG. 39). The prepreg 240a is in this state is hardened
by heating to form the resin layer 240 (FIG. 40). As a result, the
internal board wiring pattern 290, post electrodes 220 and
semiconductor IC 230 are united by the resin layer 240. The
transfer board 201 and transfer board 206 are then peeled off to
obtain a unitary laminated body (FIG. 41). The planar positional
relationship between the post electrodes 220 and stud bumps 232
coincides substantially with the planar positional relationship
between the locating holes 201a and locating holes 201b formed in
the transfer board 201. The positional relationship between the two
is therefore substantially fixed.
[0137] The surface from which the post electrodes 220 and stud
bumps 232 protrude is then overlaid with a prepreg 250a so as to
completely cover the protruding post electrodes 220 and stud bumps
232 (FIG. 42). The prepreg 250a is hardened by application of heat
to form the resin layer 250, whereafter the surface region thereof
is removed by grinding or blasting to expose the post electrodes
220 and stud bumps 232 (FIG. 43).
[0138] Next, the thin under conductor layer 260 is formed to
completely cover the surface on the side where the resin layer 250
is formed, and the thin under conductor layer 261 is formed to
completely cover the resin layer 240 (FIG. 44). In other words, an
under conductor layer is formed on either surface of the laminated
body. Next, photosensitive dry films 207 and 208 are attached to
the surfaces of the laminated body, i.e., to the surface of the
under conductor layer 260 and the surface of the under conductor
layer 261 (FIG. 45). The dry films 207 and 208 are exposed using
photomasks (not shown), whereby the dry film 207 is removed at the
regions 270a and 271a where the upper board wiring patterns 270 and
271 are to be formed and the dry film 208 is removed at the regions
210a and 211a where the lower board wiring patterns 210 and 211 are
to be formed (FIG. 46). This exposes the under conductor layer 260
at the regions 270a and regions 271a, and exposes the under
conductor layer 261 at the regions 210a and regions 211a.
[0139] Here again, as shown in FIG. 46, the regions 270a where the
upper board wiring pattern 270 is to be formed include regions
lying opposite the stud bumps 232. However, since the positional
relationship between the stud bumps 232 and the post electrodes 220
is substantially fixed in the planar direction, the regions of the
under conductor layer 260 corresponding to the stud bumps 232 can
be accurately exposed.
[0140] After portions of the under conductor layers 260 and 261
have been exposed in this manner, electroplating is conducted with
the under conductor layers 260 and 261 as substrates. This forms
the upper board wiring patterns 270 and 271 at the regions 270a and
271a where the under conductor layer 260 is exposed and forms the
lower board wiring patterns 210, 211 at the regions 210a and 211a
where the under conductor layer 261 is exposed (FIG. 47). The dry
films 207 and 208 are then peeled off to obtain a laminated body
having the upper board wiring patterns 270 and 271 formed on the
surface of the under conductor layer 260 and having the lower board
wiring patterns 210 and 211 formed on the surface of the under
conductor layer 261 (FIG. 48).
[0141] An etchant is then used to remove (by soft etching) the
unnecessary under conductor layer 260 at portions where the upper
board wiring patterns 270 and 271 are not formed and also remove
(by soft etching) the unnecessary under conductor layer 261 at
portions where the lower board wiring patterns 210 and 211 are not
formed (FIG. 49). Next, the surfaces of the laminated body are
covered with the photosensitive protective layers 280, 281, and
portions of the protective layers 280, 281 and the resin layer 250
that correspond to the regions where capacitors and other passive
components are to be mounted are removed. Finally, the passive
components are mounted to complete the module with embedded
semiconductor IC 200 shown in FIG. 32.
[0142] As explained in the foregoing, the transfer board 201 having
the locating holes 201a and 201b is used to fabricate the module
with embedded semiconductor IC 200 of this embodiment. The
positional relationship between the stud bumps 232 and post
electrodes 220 in the planar direction is therefore substantially
fixed. As a result, deviation in the positional relationship
between the stud bumps 232 and the post electrodes 220 in the
planar direction can be held to the minimum to enable use of even a
semiconductor IC 230 having a very narrow electrode pitch of 100
.mu.m or smaller, e.g., 60 .mu.m.
[0143] In addition, the formation of the internal board wiring
pattern 290 in this embodiment makes it possible to implement a
more complex wiring pattern.
[0144] In the method of fabrication described in the foregoing, the
formation of the resin layer 250 is followed by grinding or
blasting of its surface to expose the post electrodes 220 and stud
bumps 232 (see FIG. 43). However, as was explained with reference
to FIGS. 25 to 31, the exposure of the post electrodes 220 and stud
bumps 232 can instead be achieved by using a laser or the like to
form holes. In such a case, if hole-opening is also carried out
with respect to portions of the internal board wiring pattern 290,
connection between the internal board wiring pattern 290 and the
other wiring patterns and the like can be readily achieved.
[0145] The present invention is in no way limited to the
aforementioned embodiments, but rather various modifications are
possible within the scope of the invention as recited in the
claims, and naturally these modifications are included within the
scope of the invention.
[0146] In the module with embedded semiconductor IC 100 shown in
FIG. 1, for example, the lower board wiring patterns 110 and 111
are embedded in the resin layer 140. However, the lower board
wiring patterns 110 and 111 can instead be formed on the surface of
the resin layer 140 by, in the pressing step shown in FIG. 14,
using the transfer board 206 shown in FIG. 39 in place of the
transfer board 101, and then conducting the steps shown in FIGS. 44
to 49.
[0147] On the other hand, in the case of the module with embedded
semiconductor IC 200 shown in FIG. 32, the lower board wiring
patterns 210 and 211 can be embedded in the resin layer 240 by, in
the pressing step shown in FIG. 39, using the transfer board 101
shown in FIGS. 10 and 14 instead of the transfer board 206, and
then conducting the steps shown in FIGS. 19 to 24.
[0148] Moreover, it is possible to form both the lower board wiring
pattern 110 embedded in the resin layer 140 (240) and the lower
board wiring patterns 210 and 211 formed on the surface of the
resin layer 140 (240). In this case, in order to establish
insulation, a layer like the resin layer 150 (250) needs to be
interposed between embedded lower board wiring pattern 110 and the
lower board wiring patterns 210 and 211 formed on the surface.
[0149] In either embodiment, the transfer boards are in the end
peeled off. However, it is possible, for example, to use as one of
the transfer boards a multilayer substrate that is provided with
multiple sets of internal wiring and is not peeled off after
pressing but left intact to be used as part of the module with
embedded semiconductor IC. For instance, in the pressing step shown
in FIG. 39, a multilayer substrate formed with the post electrodes
220 can be used in place of the transfer board 206 formed with the
post electrodes 220 and this multilayer substrate can be left
intact (not peeled off) for use as part of the module with embedded
semiconductor IC.
[0150] Further, in either embodiment, the transfer board 106 (201)
is positioned with respect to the transfer board 101 (206) by
inserting the post electrodes 120 (220) into the locating holes
106b (201b) formed in the transfer board 106 (201) (FIGS. 14 and
39). However, the positioning need not rely on the insertion of the
post electrodes into the locating holes. For instance, it is
possible to set the height of the post electrodes approximately
equal to the thickness of the prepreg (140a, 240a) and position the
post electrodes via the locating holes by use of image recognition.
In this case, accurate positioning can be achieved without
inserting the post electrodes into the locating holes. Even in the
case of inserting the post electrodes into the locating holes,
concurrent use of positioning by means of image recognition not
only enables precise positioning even if the diameter of the
locating holes is set considerably larger than the diameter of the
post electrodes but also enhances working efficiency.
[0151] In the module with embedded semiconductor IC 100 shown in
FIG. 1, the back surface 130b and peripheral surface 130c of the
semiconductor IC 130 are totally in contact with the resin layer
140, and the main surface 130a of the semiconductor IC 130 is
totally in contact with the resin layer 150. In the case where the
resin layer 140 and resin layer 150 are made of different
materials, however, it suffices for at least part of the resin
layer 140 to be in contact with the back surface 130b and
peripheral surface 130c of the semiconductor IC 130 and for the
resin layer 150 to be in contact with at least the stud bumps 132.
The same is true of the module with embedded semiconductor IC 200
shown in FIG. 32. Therefore, it is acceptable for the interface
between the resin layer 140 and resin layer 150 to be located below
the main surface 130a of the semiconductor IC 130, as shown in FIG.
50, or for the interface between the resin layer 140 and resin
layer 150 to be located above the main surface 130a of the
semiconductor IC 130, as shown in FIG. 51.
[0152] It is worth noting, however, that the configuration shown in
FIG. 50 increases the area of contact between the semiconductor IC
130 and resin layer 150, with the result that mechanical protection
with respect to the semiconductor IC 130 is somewhat lower than in
the configurations shown in FIGS. 1 and 32 (configurations in which
the interface between the resin layer 140 and resin layer 150
coincides with the main surface 130a of the semiconductor IC 130).
On the other hand, the configuration shown in FIG. 51 brings the
stud bumps 132 into partial contact with the resin layer 140, with
the result that the electrical properties of the signals handled by
the semiconductor IC 130 become somewhat inferior to those in the
case of the configuration shown in FIGS. 1 and 32.
[0153] As explained in the foregoing, the present invention can
provide a module with embedded semiconductor IC that utilizes a
semiconductor IC with a very narrow electrode pitch. In addition,
the present invention enables simultaneous achievement of both good
semiconductor IC physical protection and excellent electrical
properties.
* * * * *